Just a reference, Galatians 5:19 mentions fornication (among other things) with the implication that it is "against the Spirit". It is among a list of "lusts of the flesh".

Actually, I read that one before my post. Here it is in its entirety:

Gal 5:19 Now the works of the flesh are manifest, which are [these]; Adultery, fornication, uncleanness, lasciviousness, Gal 5:20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, Gal 5:21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told [you] in time past, that they which do such things shall not inherit the kingdom of God.

And here is their definition of that Greek word:1) illicit sexual intercoursea) adultery, fornication, homosexuality, lesbianism, intercourse with animals etc.b) sexual intercourse with close relatives; Lev. 18c) sexual intercourse with a divorced man or woman; Mk. 10:11,122) metaph. the worship of idolsa) of the defilement of idolatry, as incurred by eating the sacrifices offered to idols

Evidently that word could mean anything from sleeping with someone who is divorced, to eating a sacrament offered to an idol. In other words, the original Greek word doesn't specify sex between unmarried people. There IS no word in the bible that means that.